The Flow Patterns in Deformation Process of Vortex Ring

Abstract

The structure of a vortex ring in deformation process were investigated by means of smoke visualization technique. The photographs of the flow pattern of a section perpendicular to the axis of a vortex ring were taken continuously with a high-speed video camera. The solid picture of a vortex ring was obtained by constructing these photographs with a computer graphics tool. As the vortex ring travelled downstream, the circumferential distortion of a solid picture appeared regularly on its surface and grew into the polygon. At final stage, i.e., just before collapse of the vortex ring, it seemed that a pair of rings might enclose the vortex core of vortex ring. These pair of rings were not combined with the vortex core. The pair of rings may be constructed of a small pair of vortex ring which are generated due to the centrifugal instability.